Variable condenser for tuning electric oscillating circuits



Nov. 9 1926.

' K. J. G. AHLSTRAND VARIABLE] CONDENSER FOR TUNING ELECTRIC CSCILLATING CIRCUITS Filed Sept. 2, 1925 Patented Nov. 9, 1926.

tittii ED STATES FFEQE.

eater VARIABLE CONDENSER FOR TUNING- ELECTRIC OSCILLATING CIRCUITS.

Application filed September 2, 1925. Serial No. 54,022, and in Sweden May 27, 1925.

Variable condensers used for tuning electric oscillating circuits consist as is well known of a system of fixed Plates and a m tell: of movable plates, the latter usually provided on a rotatable axle so that hen a they niay be turned into the spaces between the fixed plates. As an accurate adjustment of the two systems in relation to each other is of great importance it is usual to provide the condenser with a special device for this purpose, a so called fine tuning mechanism. It is desirable to be able to control the final adjustment by means of a member that is located centrically in relation to the hand wheel on the axle of the condenser supporting the movable system of plates. The object of my present invention to provide a device which renders it possible to make a very accurate final adjustment of the condenser by means of a line tuning axle or spindle having the same axis of rotation as the axle or spindle supporting the movable system of plates. The invention consists in the combinations and arrangements of parts described hereinbelow ith reference to the accompanying drawings and pointed out in the claim.

Fig. 1 of the drawing shows an axial cross section of an embodiment of my invention on line 11 of Fig. 2, and Fig. 2 shows a section on line 22 of Fig. 1, the hand wheel being removed.

Referring to the drawing 2 designates an axle adapted to support the movable plates of condenser not shown) and protruding tnrouglra wall l6'serving as a base plate for said condenser. On the axle 2 is provided' sleeve 17 which is secured to the axle by means of a set screw 18 or in any other suitable manner. To the sleeve 17 is rigidly secured a disc 19 having a conical flange 19 Ahand wheel 14 is in its turn rigid- 1y secured to said disc 19. On a conical portion 17 'of the sleeve 17 is journalled a sleeve 20 formed at its outer or upper end with fingers 21 extending through corresponding openings. 24 in the disc 19. The said fingers engage an eccentric 6 formed on thehollow axle 5 which is rotatably journalled on a pin 23 extending from the sleeve 17. On the sleeve 20 is rotatably mounted a wheel 7 to which are rigidly secured a number of yielding arms 22 of which always one or more are in frictional engagement with the wall 16 and force the wheel 7 into engagement with the flange 19 of the disc 19. i

The device now described works as follows. \Vhen the eccentric is rotated by means of the knob 15 the upper end of the sleeve 20 will make a circling movement and bring the circumference of the wheel 7 in successive engagement with the flange 19 The arm or arms 22 nearest to the point of engagement between the wheel 7 and the flange 19 are pressed against the wall while the other arms 22 are lifted therefrom owing to the inclined position of the wheel 7 The latter will thus to some extent be prevented from rotating and will-0n account thereof impart a slow rotating movement to the disc 19 the axle 2 and By adjusting the sleeve 17 on the axle 2 may however also be rotated direct by means of the hand wheel 14 the wheel 7 being capable of sliding on the flange 19 while the arms 22 can slide on the wall 16. By adjusting the sleeve 17 on the axle 2 the strength of friction between the wheel 7 and 'the flange 19 as well as bet-ween {he prms 22 and the wall 16 may be reguatec.

Having now described my invention, What I claim is:

In a condenser for tuning oscillating circuits, the combination of two axles having a common axis of rotation, a friction member on one of said axles in centric relation thereto, a hand wheel rigidly secured to subscribed my name.

KARL JOHAN GERHARD AHLSTRAND. 

